… | |
… | |
16 | |
16 | |
17 | cede; |
17 | cede; |
18 | |
18 | |
19 | DESCRIPTION |
19 | DESCRIPTION |
20 | This module collection manages coroutines. Coroutines are similar to |
20 | This module collection manages coroutines. Coroutines are similar to |
21 | threads but don't run in parallel. |
21 | threads but don't run in parallel at the same time even on SMP machines. |
|
|
22 | The specific flavor of coroutine use din this module also guarentees you |
|
|
23 | that it will not switch between coroutines unless necessary, at |
|
|
24 | easily-identified points in your program, so locking and parallel access |
|
|
25 | are rarely an issue, making coroutine programming much safer than |
|
|
26 | threads programming. |
|
|
27 | |
|
|
28 | (Perl, however, does not natively support real threads but instead does |
|
|
29 | a very slow and memory-intensive emulation of processes using threads. |
|
|
30 | This is a performance win on Windows machines, and a loss everywhere |
|
|
31 | else). |
22 | |
32 | |
23 | In this module, coroutines are defined as "callchain + lexical variables |
33 | In this module, coroutines are defined as "callchain + lexical variables |
24 | + @_ + $_ + $@ + $^W + C stack), that is, a coroutine has it's own |
34 | + @_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own |
25 | callchain, it's own set of lexicals and it's own set of perl's most |
35 | callchain, its own set of lexicals and its own set of perls most |
26 | important global variables. |
36 | important global variables. |
27 | |
37 | |
28 | $main |
38 | $main |
29 | This coroutine represents the main program. |
39 | This coroutine represents the main program. |
30 | |
40 | |
… | |
… | |
66 | |
76 | |
67 | # create a new coroutine that just prints its arguments |
77 | # create a new coroutine that just prints its arguments |
68 | async { |
78 | async { |
69 | print "@_\n"; |
79 | print "@_\n"; |
70 | } 1,2,3,4; |
80 | } 1,2,3,4; |
|
|
81 | |
|
|
82 | async_pool { ... } [@args...] |
|
|
83 | Similar to "async", but uses a coroutine pool, so you should not |
|
|
84 | call terminate or join (although you are allowed to), and you get a |
|
|
85 | coroutine that might have executed other code already (which can be |
|
|
86 | good or bad :). |
|
|
87 | |
|
|
88 | Also, the block is executed in an "eval" context and a warning will |
|
|
89 | be issued in case of an exception instead of terminating the |
|
|
90 | program, as "async" does. As the coroutine is being reused, stuff |
|
|
91 | like "on_destroy" will not work in the expected way, unless you call |
|
|
92 | terminate or cancel, which somehow defeats the purpose of pooling. |
|
|
93 | |
|
|
94 | The priority will be reset to 0 after each job, otherwise the |
|
|
95 | coroutine will be re-used "as-is". |
|
|
96 | |
|
|
97 | The pool size is limited to 8 idle coroutines (this can be adjusted |
|
|
98 | by changing $Coro::POOL_SIZE), and there can be as many non-idle |
|
|
99 | coros as required. |
|
|
100 | |
|
|
101 | If you are concerned about pooled coroutines growing a lot because a |
|
|
102 | single "async_pool" used a lot of stackspace you can e.g. |
|
|
103 | "async_pool { terminate }" once per second or so to slowly replenish |
|
|
104 | the pool. |
71 | |
105 | |
72 | schedule |
106 | schedule |
73 | Calls the scheduler. Please note that the current coroutine will not |
107 | Calls the scheduler. Please note that the current coroutine will not |
74 | be put into the ready queue, so calling this function usually means |
108 | be put into the ready queue, so calling this function usually means |
75 | you will never be called again unless something else (e.g. an event |
109 | you will never be called again unless something else (e.g. an event |
… | |
… | |
98 | "Cede" to other coroutines. This function puts the current coroutine |
132 | "Cede" to other coroutines. This function puts the current coroutine |
99 | into the ready queue and calls "schedule", which has the effect of |
133 | into the ready queue and calls "schedule", which has the effect of |
100 | giving up the current "timeslice" to other coroutines of the same or |
134 | giving up the current "timeslice" to other coroutines of the same or |
101 | higher priority. |
135 | higher priority. |
102 | |
136 | |
|
|
137 | Returns true if at least one coroutine switch has happened. |
|
|
138 | |
|
|
139 | Coro::cede_notself |
|
|
140 | Works like cede, but is not exported by default and will cede to any |
|
|
141 | coroutine, regardless of priority, once. |
|
|
142 | |
|
|
143 | Returns true if at least one coroutine switch has happened. |
|
|
144 | |
103 | terminate [arg...] |
145 | terminate [arg...] |
104 | Terminates the current coroutine with the given status values (see |
146 | Terminates the current coroutine with the given status values (see |
105 | cancel). |
147 | cancel). |
106 | |
148 | |
107 | # dynamic methods |
149 | # dynamic methods |
… | |
… | |
126 | $is_ready = $coroutine->is_ready |
168 | $is_ready = $coroutine->is_ready |
127 | Return wether the coroutine is currently the ready queue or not, |
169 | Return wether the coroutine is currently the ready queue or not, |
128 | |
170 | |
129 | $coroutine->cancel (arg...) |
171 | $coroutine->cancel (arg...) |
130 | Terminates the given coroutine and makes it return the given |
172 | Terminates the given coroutine and makes it return the given |
131 | arguments as status (default: the empty list). |
173 | arguments as status (default: the empty list). Never returns if the |
|
|
174 | coroutine is the current coroutine. |
132 | |
175 | |
133 | $coroutine->join |
176 | $coroutine->join |
134 | Wait until the coroutine terminates and return any values given to |
177 | Wait until the coroutine terminates and return any values given to |
135 | the "terminate" or "cancel" functions. "join" can be called multiple |
178 | the "terminate" or "cancel" functions. "join" can be called multiple |
136 | times from multiple coroutine. |
179 | times from multiple coroutine. |
|
|
180 | |
|
|
181 | $coroutine->on_destroy (\&cb) |
|
|
182 | Registers a callback that is called when this coroutine gets |
|
|
183 | destroyed, but before it is joined. The callback gets passed the |
|
|
184 | terminate arguments, if any. |
137 | |
185 | |
138 | $oldprio = $coroutine->prio ($newprio) |
186 | $oldprio = $coroutine->prio ($newprio) |
139 | Sets (or gets, if the argument is missing) the priority of the |
187 | Sets (or gets, if the argument is missing) the priority of the |
140 | coroutine. Higher priority coroutines get run before lower priority |
188 | coroutine. Higher priority coroutines get run before lower priority |
141 | coroutines. Priorities are small signed integers (currently -4 .. |
189 | coroutines. Priorities are small signed integers (currently -4 .. |
… | |
… | |
164 | $olddesc = $coroutine->desc ($newdesc) |
212 | $olddesc = $coroutine->desc ($newdesc) |
165 | Sets (or gets in case the argument is missing) the description for |
213 | Sets (or gets in case the argument is missing) the description for |
166 | this coroutine. This is just a free-form string you can associate |
214 | this coroutine. This is just a free-form string you can associate |
167 | with a coroutine. |
215 | with a coroutine. |
168 | |
216 | |
169 | UTILITY FUNCTIONS |
217 | GLOBAL FUNCTIONS |
|
|
218 | Coro::nready |
|
|
219 | Returns the number of coroutines that are currently in the ready |
|
|
220 | state, i.e. that can be swicthed to. The value 0 means that the only |
|
|
221 | runnable coroutine is the currently running one, so "cede" would |
|
|
222 | have no effect, and "schedule" would cause a deadlock unless there |
|
|
223 | is an idle handler that wakes up some coroutines. |
|
|
224 | |
|
|
225 | my $guard = Coro::guard { ... } |
|
|
226 | This creates and returns a guard object. Nothing happens until the |
|
|
227 | objetc gets destroyed, in which case the codeblock given as argument |
|
|
228 | will be executed. This is useful to free locks or other resources in |
|
|
229 | case of a runtime error or when the coroutine gets canceled, as in |
|
|
230 | both cases the guard block will be executed. The guard object |
|
|
231 | supports only one method, "->cancel", which will keep the codeblock |
|
|
232 | from being executed. |
|
|
233 | |
|
|
234 | Example: set some flag and clear it again when the coroutine gets |
|
|
235 | canceled or the function returns: |
|
|
236 | |
|
|
237 | sub do_something { |
|
|
238 | my $guard = Coro::guard { $busy = 0 }; |
|
|
239 | $busy = 1; |
|
|
240 | |
|
|
241 | # do something that requires $busy to be true |
|
|
242 | } |
|
|
243 | |
170 | unblock_sub { ... } |
244 | unblock_sub { ... } |
171 | This utility function takes a BLOCK or code reference and "unblocks" |
245 | This utility function takes a BLOCK or code reference and "unblocks" |
172 | it, returning the new coderef. This means that the new coderef will |
246 | it, returning the new coderef. This means that the new coderef will |
173 | return immediately without blocking, returning nothing, while the |
247 | return immediately without blocking, returning nothing, while the |
174 | original code ref will be called (with parameters) from within its |
248 | original code ref will be called (with parameters) from within its |